In many industrial fields, filiform or web-shaped materials are wound on tubular winding cores made of plastic, cardboard or other material. These tubular winding cores (hereof also simply called “cores”) are accumulated in a storage unit and gradually supplied to the machine which winds the filiform or web-shaped material. The products wound on the cores can be, for example, plastic films, fabrics, non-wovens, paper, tissue paper, or other products in film or sheet form in general.
In the paper converting industry, converting lines with one or more unwinders are used for making rolls of toilet paper, kitchen paper and similar products. The unwinders unwind the web like material from corresponding large diameter rolls and supply it to a rewinder. The rewinder winds predetermined amounts of web-shaped material on cores, which are usually made of cardboard. The cores are made by so-called tube making machines, which are generally arranged by the side of the rewinder. The cores are frequently simply piled up in bin accumulators from where they are taken by a conveyor belt or chain and introduced one at a time in the rewinder. The supply frequency of the cores may currently be in the order of 40 cores/minute.
The rolls formed by the rewinder present a diameter which is equal to the diameter of the finished product to be marketed and a length equal to a multiple of the length of the finished product. The rolls (also called “logs”) are, therefore, cut to form the finished smaller rolls.
The paper converting industry tends to use reminders capable of winding rolls with increasingly larger axial lengths, i.e. machines which can handle increasingly wider web like material. It has bead that very long cores tend to assume irregular positions in the currently employed accumulators and even present the tendency to twist one on the other and consequently break, jamming the automatic flow to the rewinder. This entails considerable production problems.
Similar problems may occur in other sectors in which elongated shape products, specifically products with modest flexural resistance, are accumulated and held in an accumulator.
Currently, storage units or accumulators for temporarily accumulating the rolls made by rewinders with two flexible members in the form of reciprocally parallel chains are known in the art. Continuous oscillating supports are fastened to the chains and extend from one of the flexible members to the other, on each of which support a roll is arranged. The flexible members are arranged at a distance which exceeds the length of the roll to be handled. An example of accumulator of this type is described in U.S. Pat. No. 6,053,304.
This type of accumulator is not suitable for handling elongated light objects with small transversal dimensions (such as winding tubes or cores) due to the need to arrange costly and cumbersome oscillating supports which increase the cost of the accumulator.